Sleep fragmentation of OSA contributed to elevated activity of the sympathetic nervous system, hypothalamic–pituitary–adrenal (HPA) axis and oxidative stress reaction, which subsequently led to decreased uptake of insulin-mediated glucose and secretion of insulin, increased levels of ROS, inflammation and pancreatic β-cell apoptosis, consequently resulting in reduced glucose tolerance and IR (14). Here, INS is linked to obstructive sleep apnea syndrome.